The invention relates to an over-center hinge for cabinet doors, which has a supporting-wall-related part which can be fastened to the supporting wall of a cabinet, and a door-related part articulated by a link mechanism to the supporting-wall-related part and made in the form of a cup for installation in a recess in the door, and having in its peripheral wall adjacent its bottom a tongue. The tongue is mounted for pivoting over a given angular amount under the bias of a compression spring urging it towards the interior of the cup. A contact surface provided at the link end of the supporting-wall-related part slides, during a portion of the opening and closing movement, between the hinge-closed position and a dead-center position along the portion of the profile of the tongue which slopes upwardly towards the cup interior from the bottom thereof, and forces the door into the closed position.
In these known hinges (German Pat. No. 2,016,398 and German Pat. No. 2,122,857), the tongue is given its maximum deflection and its spring its maximum compression by the contact surface of the supporting-wall-related part of the hinge, while, upon the further movement of the contact surface, whether in the closing or opening direction, it performs a movement which slightly relaxes the compression spring. Since this movement is needed in order to urge the tongue against the contact surface with sufficient force to hold the door closed, the compression spring also exerts a force through the tongue, which, when the dead center is passed during the opening movement, imparts to the door mounted with the hinge an acceleration in the direction of opening. In may applications, such an over-center characteristic is not desired, and instead hinges are needed which do exercise a holding force on the door in the immediate vicinity of its closed position, but otherwise permit an effortless movement of the door by hand, especially without any acceleration of the door in the opening direction. Such an over-center characteristic, however, cannot be achieved in the known hinge equipped with the spring-biased tongue pivotingly mounted in the hinge-mounting cup, because the movement of the tongue that is needed for the production of the closing force is necessarily also produced during the opening movement of the door past the dead center, resulting in the undesired opening force. In such cases, in which the production of an opening force is not desired, hinges have heretofore been used which have a mechanism of complex design and therefore high cost of manufacture, in which the controlling of the over-center behavior is accomplished with a control cam cooperating with a spring-biased lever provided, as a rule, with a roller to reduce friction (German OS No. 1,801,310 and OS No. 2,401,178). Since no space is available in the hinge-mounting cup for such a control cam mechanism, it is disposed in the forward end of the supporting-wall-related part of the hinge, and this also increases the amount of space required and the necessary dimensions of the supporting-wall-related part of the hinge.
It is the object of the invention to improve the known over-center hinges provided with a tongue pivoted within the hinge-mounting cup, such that they will have an over-center characteristic in which the over-center effect will occur substantially only in the range between the closed position and the dead-center position of the door, and will be directed exclusively in the closing direction. There will be no application of force in the opening direction past the dead-center position, i.e., the door equipped with such a hinge can be swung without any resistance from the open position to the dead-center position or a point just preceding same, and vice-versa.